This application claims the priority of Korean Patent Application No. 2004-66137, filed on Aug. 21, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a method and system for monitoring a broadcast slot used in a mobile station and, more particularly, to a method and system for monitoring a broadcast slot used in a mobile station, which is capable of reducing battery power consumption in the mobile station by turning broadcast slot monitoring off except during user-selected broadcast times.
2. Description of the Related Art
Upon power-up, a mobile station (MS) selects a mobile communication system where the mobile station has been registered, synchronizes the mobile communication system over a pilot channel and a synchronous (Sync) channel, and monitors a paging channel in an idle state. During the idle state, when a user receives from a base station (BS) a paging channel message which needs a response, makes a telephone call using the mobile station, or registers the location of the mobile station, the mobile station is switched to an access state and transmits a necessary message to the base station over an access channel.
A message transmitted over the paging channel includes an overhead message related to an overall system configuration, and a designation message related to a response to a paging signal of a mobile station. In more detail, the overhead message is repeatedly transmitted to all mobile stations over a paging channel slot, while the designation message is transmitted to a specific mobile station over a slot specified in a slotted mode. On the other hand, a broadcast message is transmitted over a broadcast slot rather than the slot specified in the slotted mode at a broadcast slot cycle defined in an extended system parameter message which is a kind of the overhead message.
The mobile station operates a reception circuit during 160˜240 msec (including a time when the mobile station wakes up from the idle state) at regular intervals specified in the slotted mode (e.g., about 2.6 seconds if a slot cycle index is 2) to monitor whether or not to be paged. Consequently, the battery lifetime of the mobile station depends on the monitoring period of the paging channel slot.
Since the broadcast message is transmitted over the broadcast slot rather than the slot specified in the slotted mode, the mobile station monitors the broadcast slot in addition to the paging channel slot. On the other hand, a conventional mobile station opens the broadcast slot all the time even though a broadcast time of each broadcast channel is fixed in advance. Accordingly, the conventional mobile station unnecessarily monitors the broadcast slot during non-broadcast times, resulting in reduced battery lifetime of the mobile station.